Light Emitting Element With Metal Bulk Support Structure
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Solution Overview
Problem
Flip chip type light emitting elements face issues with heat dissipation efficiency, current spreading, and mechanical reliability, leading to reduced luminous efficacy and vulnerability to stress and strain during substrate separation.
Innovation Solution
A light emitting element design featuring a mesa structure with protrusions, a support structure of metal bulks, and insulation layers to improve current spreading and heat dissipation, while preventing excessive contact region bias and enhancing mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick metal pad or polymer is disposed under the light emitting structure to prevent stress and strain, then mechanical reliability is improved, but cracks are generated mainly at the center of the light emitting structure near an upper side of the polymer
Solution Approach 1:
The patent introduces a stress relief layer as an intermediary component between the light emitting structure and the substrate. This stress relief layer has a coefficient of thermal expansion between that of the substrate and the light emitting structure, acting as a buffer to reduce stress concentration and prevent crack generation at the center of the light emitting structure while maintaining mechanical reliability.
2Temperature
If electric current is supplied through metal bulk to a certain contact region, then heat dissipation is improved, but current spreading is insufficient and luminous efficacy deteriorates
Solution Approach 1:
The patent divides the contact region into multiple segmented contact regions instead of a single large contact region. This segmentation allows current to spread more uniformly across the semiconductor layer while maintaining effective heat dissipation paths through the metal bulk, thereby improving luminous efficacy without sacrificing heat dissipation efficiency.
Solution Approach 2:
The patent creates different local qualities in the contact region by varying the distribution and size of segmented contact regions. Areas with higher current density have smaller contact regions, while areas requiring better heat dissipation have larger contact regions, optimizing both current spreading and heat dissipation locally across the structure.
3Ease of manufacture
If the contact region is concentrated in a certain area, then manufacturing is simplified, but light emission is not efficient in regions where the electrode does not contact the semiconductor layer
Solution Approach 1:
The patent transitions from a two-dimensional planar contact region to a three-dimensional structured contact region with multiple levels and patterns. This dimensional change allows the contact region to maintain manufacturing simplicity while enabling current to reach and activate light emission across the entire semiconductor layer surface through vertical and lateral current paths.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design achieves improved luminous efficacy by ensuring efficient current spreading and heat dissipation, while preventing damage from stress and strain, thus enhancing the reliability and performance of the light emitting element.
Implementation Method 1
a support structure including a first metal bulk and a second metal bulk disposed on a lower surface and a side surface of the second insulation layer to be separated from each other and electrically connected to the first electrode and the second electrode through the openings, respectively
Implementation Method 2
the light emitting element emits light upon receiving power through an electrode electrically connected to a semiconductor layer
Data Source
AI summary
A light emitting element according to an embodiment of the present invention comprises a first conductive-type semiconductor layer including a contact region on the lower surface thereof, a light emitting structure which includes a mesa including a second conductive-type semiconductor layer and an active layer, a second electrode, a first insulation layer, an electrode cover layer, a first electrode, a second insulation layer, and a support structure. In addition, the mesa may include a body part and a plurality of protrusion parts protruding from the body part, the contact region may be disposed between the protrusion parts, and a part of the contact region may overlap with a second metal bulk in the vertical direction. Accordingly, current spreading efficiency can be improved, and thus luminance efficiency can be more improved.